Screw cap closures (closures) are well known from the prior art and are a subject of continuous optimization. One attempt is to reduce the weight of the closure because the major share of the price is caused by the material used to make the closure. Therefore, in other words, reduction of the material used to make the closure means a reduction of the price of the closure. Furthermore, less material consumption results in an improved environmental compatibility.
From the same inventor several patent applications are known in the field of the invention, which are primarily directed to sealing technology and/or closures. Examples are WO06024550, WO06024656, WO06097151, WO03022701, WO0056615, WO0056616, WO9903746, WO9402371, WO8912584, U.S. Pat. No. 6,874,648 and USD613162.
EP0076778 of Albert Obrist AG was filed in 1982 and is directed to a closure cap made of plastics material, which has a circular outer sealing lip having a thickness which continuously decreases versus its free end. The outer sealing lip is arranged in the region of the joint between an outer vertical skirt and a disc like top portion and points obliquely inwards. At its smallest diameter, the sealing lip has a rounded sealing portion. Below the sealing portion, the sealing lip is widened outwards in the manner of a funnel to receive a container opening. However, due to the obliged arrangement of the sealing lip, the sealing lip often tends to be distorted during application, especially crooked application onto a neck of a container. A further disadvantage consists in that, due to the inclined arrangement, this seal is relatively rigid and therefore not very good in adjusting in lateral direction.
U.S. Pat. No. 4,489,845 was filed in 1984 and assigned to Albert Obrist AG. U.S. Pat. No. 4,489,845 is directed to a screw-cap for closing a container opening. The cap has a sealing lip which is affixed to the cap top. The inner side-wall of the outer sealing lip has a diameter which is greater than the outer diameter of the container outer wall. A clamping device, which can be designed as an inner seal, creates a contraction of the cap top when the screw-cap is screwed onto the container due to deformation of the outer shell of the closure, by which means the sealing lip shall be pressed against the container mouth. In this manner the sealing lip is only pressed radially against the container mouth during the course of the screwing-on process. Thereby, over-stretching and damage to the material of the sealing lip shall be prevented. In an engaged position the sealing lip engages around the upper outer rim of the neck of a container opening. One disadvantage is that the described deformation of the closure is related to extensive operating forces. A further disadvantage consists in that the outer shell tends to break due to extensive stress and deformation (stress cracking), which results in complete failure of the closure and loss of the product.
WO03011699 filed in 2002 by Bericap is directed to a closure cap comprising an internal sealing skirt, which is substantially truncated and converges from the sealing skirt base towards the free end of the sealing skirt. The inside of the sealing skirt is designed to cooperate with the outside of the neck. The internal diameter of the sealing skirt towards its free end portion is designed smaller than the external diameter of the neck. As described, the closure can comprise an annular v-notch designed to improve attachment of a liner to the rim of the neck or contact between the liner and the rim.
Further patent publications showing several sealing technologies and/or closures are e.g. JP57133851, JP58073551, U.S. Pat. No. 4,489,845, U.S. Pat. No. 6,874,648, JP9150846, JP3872546, JP4392873, JP2000109105, JP4456681, U.S. Pat. No. 7,014,055, WO0187725, U.S. Pat. No. 6,695,161, JP4533597, WO05039996, JP4413071, U.S. Pat. No. 7,575,121, JP2007145341 or U.S. Pat. No. 7,607,547.